Camshaft adjusting devices, particularly those working hydraulically, are sufficiently well-known in the prior art. In the hydraulic camshaft adjuster there is a vane impeller, in which vanes are formed or arranged. The vanes are situated in hydraulic chambers, which are sunk in an external rotor. The internal rotor (connected to the camshaft) can be adjusted relative to the external rotor between an ‘advanced stop’ and a ‘retarded stop’ by way of corresponding admission of hydraulic fluid to the respective side of the hydraulic chambers. The flow of hydraulic oil is here controlled by an electrically actuated directional valve.
The rotary motion of the crankshaft is in this case transmitted to the external rotor via a gearwheel, which is rotationally fixed to the external rotor. In the prior art there are known solutions in which the gearwheel is embodied as a chain sprocket and is arranged at the outer circumference of the external rotor or rotationally fixed to the external rotor. Examples of this are disclosed in DE 100 54 798 A1, in DE 10 2004 007 050 A1, in DE 10 2004 038 695 A1 and in DE 10 2004 062 038 A1.
The camshaft is generally axially supported in the cylinder head, so that one camshaft end is first connected to the internal rotor of the camshaft adjuster by means of a central bolt or a weld. The axial support of the internal rotor in the camshaft adjuster thereby then also affords an axial support of the camshaft. The drive torque is transmitted to the external rotor by said gearwheel.
This type of axial support requires a stepped limit stop of a different diameter on the external surface of the camshaft. Producing this axial limit stop on the camshaft is disadvantageously associated with additional manufacturing and assembly outlay and thereby with corresponding costs.
This concept may furthermore forfeit the cost and weight advantages that accrue from using a continuous tube as the body of the camshaft. The camshaft must then additionally undergo radial deformation or metal cutting operations for the shaping of an axial limit stop.
A non-positive or cohesive material attachment of a limit stop element in the form of a sleeve is also associated with weight and cost disadvantages.
The gearwheel—in the form of a spur gear—is furthermore very disadvantageous for grinding processes, owing to its undercut between the end face of the toothed rim and the outer end face of the sealing cover of the adjuster. If the tooth flanks are to be ground in order to obtain an adequate toothing quality, the run-out of the grinding tool required by the production engineering process is no longer possible.